DESCRIPTION: (Adapted from applicant's description) This is an initial application submitted by a new investigator. Primary dysmenorrhea is defined as pain during the menses in the absence of a pathologic lesion and is probably caused by prostaglandin effects on the uterus. Primary dysmenorrhea is highly prevalent among adolescents. More than 50% of adolescent girls in various populations report dysmenorrhea which is severe in about 15%. Dysmenorrhea is a major cause of morbidity in adolescents leading to activity restriction and school absence. Combined oral contraceptives (COC) are a common treatment for primary dysmenorrhea. Some small laboratory studies show decreased prostaglandins associated with COC use compared to non-COC use. Larger observational studies show a lower prevalence of dysmenorrhea among COC users compared to non-COC users and improved dysmenorrhea after initiating open-label COC use. In the only randomized, double blind, placebo-controlled trial, Matthews showed modest improvement of dysmenorrhea among a small number of women using a high- dose COC compared to placebo (1968). None of the existing studies compare the efficacy of a low-dose COC with placebo in the treatment of primary dysmenorrhea. The proposed study is a double blind, randomized, placebo-controlled trial to determine the efficacy of a low-dose COC in the treatment of primary dysmenorrhea among urban, adolescent girls. Healthy girls aged 19 years or less with moderate to severe dysmenorrhea as determined by the Robinson modification of the Andersch scale will be eligible (Robinson, 1992). 150 girls will be randomized to receive either a COC containing 20 micrograms ethinyl estradiol and 0.1 milligrams levonorgestrel or a placebo. The main effect will be change in score on the pain sub-scale of the Moos Menstrual Distress Questionnaire (MDQ) after three months of treatment. This study will have 80% power to detect a 50% reduction in pain score with an alpha of .05 and a drop-out rate of 40%. Secondary outcome measures will be changes in school absence, activity restriction and medication use. Also, we plan to determine if psychological measures of depression, life-crisis events or self- concept ratings predict response to treatment. Given their efficacy in pregnancy prevention, safety, and non-contraceptive health benefits, COC may be an ideal therapy for primary dysmenorrhea in adolescent girls.